Most machine tools are designed to be operated with a stationary tool and a rotating workpiece. Turning tools and drills can be operated in this way.
If a power source is placed on a moveable carriage, then operation with a rotating tool, such as a milling tool, is made possible. Such tools are positioned in the plane of the workpiece, and generally can be moved back and forth lengthwise or longitudinally with respect to the workpiece. If the driving means of the workpiece is capable of automatically establishing exact angular positioning, then the workpiece can also be machined with high versatility along its circumference.
Tool loading and exchange systems are also known which make possible the rapid switching of boring and milling tools (see the aforementioned application and the literature cited in the file thereof). Inclined-bed machines are also known which have tool magazines which are either stationary or travel with the support carriage. Tool-loading devices with grippers are known which provide means for a tool-exchange operation.
In order to have a true y-axis machining capability, or in other words to make possible the machining of the workpiece in the y-direction, large machines have been developed with tool carriages which can be automatically moved under programmatic control in the y-direction.
So-called machining centers have been designed for complex cutting and machining operations, and these generally have multiple machining heads with stationary as well as rotating tools. These include for example turret heads, whose supply of tools can also make use of a tool exchanging system.
However, it has been very difficult with this sort of system to avoid collisions at some stage of the process of installing, changing, and operating the tools. Moreover, inexactness and errors, and even damage to the workpiece, are caused by the chips falling into the working area.